1. Field of the Invention
The invention is concerned with improvements in internal combustion engine technology, in particular spark-ignited, diesel (i.e., kerosene based) fuel burning piston engines.
2. Background of the Invention
It is desirable to use kerosene based fuels, i.e., fuels spanning JP-5 to D-2, instead of gasoline for spark ignited, piston engines under conditions where various type engines are to be used for different applications but only a single fuel is to be supplied and stored for all types of engines. Such conditions would be encountered typically in a military environment which could include the use of aviation jet engines, vehicle engines, fixed or mobile engine generator systems, etc. Under such conditions, it is considered advantageous to be able to use a single type fuel for all engines, in particular diesel type fuel, because a spark ignited 2 or 4 stroke piston engine normally burning gasoline can be converted to run on diesel fuel with minimum alterations to the basic engine being required. Non-military situations could include buses and auxiliary engines, campers and auxiliary engines, and small portable engines used where kerosene fuel is available but not gasoline.
However, two stroke or four stroke cycle spark ignited piston type internal combustion engines intended for use with diesel (i.e., kerosene based) fuels typically require special arrangements for starting the engines under cold ambient conditions, and further, while running, such engines are prone to spark plug fouling and high hydrocarbon (HC) and smoke emissions due to incomplete combustion of the fuel. Glow plugs that are typically used for starting diesel engines may not be relied on unless battery or other electrical power is available to energize the plugs, and even if the use of glow plugs is feasible, the low compression ratio of a spark ignited engine may not produce sufficiently high temperature in the charge to dependably ensure ignition during cold start conditions when a glow plug is used.
While JP-5 and light kerosene fuels flow freely under sub-freezing temperatures, heavier diesel fuels tend to cloud and congeal due to precipitation of waxes contained in such fuels, making the use of heavy diesel fuels problematic under extreme cold conditions. Fuel preheaters of various types have been used in diesel engine fuel supply systems to avoid the cold flow problems associated with such fuels.
Accordingly, there exists a need for a charge conditioning system for spark-ignited, piston-type kerosene based (diesel) fuel burning internal combustion engines that will enable dependable starting of the engine under cold ambient conditions with or without the availability of battery supplied electrical energy and which will ensure clean burning of the fuel without spark plug fouling during engine operation.
The present invention is intended to provide a starting and running system for diesel fueled spark ignited engines that will ensure dependable starting and clean running of such engines even under extreme cold ambient conditions.